U.S. patent application number 15/300467 was filed with the patent office on 2017-05-04 for antenna, antenna array, and radio communication apparatus.
This patent application is currently assigned to NEC Corporation. The applicant listed for this patent is NEC Corporation. Invention is credited to Keishi KOSAKA, Hiroshi TOYAO.
Application Number | 20170125885 15/300467 |
Document ID | / |
Family ID | 54239516 |
Filed Date | 2017-05-04 |
United States Patent
Application |
20170125885 |
Kind Code |
A1 |
KOSAKA; Keishi ; et
al. |
May 4, 2017 |
ANTENNA, ANTENNA ARRAY, AND RADIO COMMUNICATION APPARATUS
Abstract
A dual-polarized antenna in which two antenna elements are
highly integrated and the size of the whole antenna is reduced
while suppressing coupling between the two antenna elements without
having the two antenna elements overlap each other is provided. An
antenna (10) includes a conductive reflector (101) and two antenna
elements (102, 103) (antenna elements) that are arranged to be
spaced apart from each other. As shown in FIG. 3, in a projected
view on the conductive reflector (101), longitudinal directions of
the two antenna elements (102, 103) are substantially orthogonal to
each other. One of the end parts (110) of the antenna element (103)
in the longitudinal direction is positioned at an approximate
center (109) (part around the center) of the antenna element (102)
in the longitudinal direction.
Inventors: |
KOSAKA; Keishi; (Tokyo,
JP) ; TOYAO; Hiroshi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NEC Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
NEC Corporation
Tokyo
JP
|
Family ID: |
54239516 |
Appl. No.: |
15/300467 |
Filed: |
November 14, 2014 |
PCT Filed: |
November 14, 2014 |
PCT NO: |
PCT/JP2014/005722 |
371 Date: |
September 29, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01Q 15/14 20130101;
H01Q 21/24 20130101; H01Q 21/06 20130101; H01Q 1/36 20130101; H01Q
9/26 20130101; H01Q 21/00 20130101; H01Q 9/065 20130101; H01Q 1/24
20130101; H01Q 21/28 20130101 |
International
Class: |
H01Q 1/24 20060101
H01Q001/24; H01Q 21/00 20060101 H01Q021/00; H01Q 1/36 20060101
H01Q001/36; H01Q 9/06 20060101 H01Q009/06; H01Q 15/14 20060101
H01Q015/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2014 |
JP |
2014-073195 |
Claims
1. An antenna comprising: a conductive reflector; and two antenna
elements that are arranged to be spaced apart from each other,
wherein, in a projected view of the conductive reflector,
longitudinal directions of the two antenna elements are
substantially orthogonal to each other and an end part of one of
the two antenna elements in the longitudinal direction is
positioned around the center of the other one of the antenna
elements in the longitudinal direction.
2. The antenna according to claim 1, wherein each of the antenna
elements is a dipole antenna element.
3. The antenna according to claim 1, wherein: each of the antenna
elements comprises: a C-shaped conductor having a substantially C
shape; and a conductor feed line having one end connected to the
C-shaped conductor, and the C-shaped conductor is formed by cutting
out a part of a substantially ring-shaped conductor and includes a
split part, which corresponds to the cut out part formed in the
C-shaped conductor.
4. The antenna according to claim 3, wherein: each of the antenna
elements comprises a conductor feed GND part arranged to be opposed
to the conductor feed line, the conductor feed GND part has one end
that is connected to an outer edge of the C-shaped conductor, and
the conductor feed GND part has another end that is connected to
the conductive reflector.
5. The antenna according to claim 4, wherein: the outer edge of the
C-shaped conductor extends in a C shape, and the one end of the
conductor feed GND part is connected to the approximate center of
the outer edge that extends in the C shape.
6. The antenna according to claim 3, wherein: each of the antenna
elements comprises at least one auxiliary conductor that is
electrically connected to one of two conductors of the C-shaped
conductor that are opposed to each other in the split part and is
opposed to the other one of the two conductors of the C-shaped
conductor.
7. The antenna according to claim 3, wherein: the C-shaped
conductor is formed with an approximately rectangular flat shape,
and each of the antenna elements comprises a conductor radiation
part connected to at least one of two outer edges that are adjacent
to an outer edge where the split part is formed among four outer
edges of the C-shaped conductor.
8. The antenna according to claim 3, wherein: the C-shaped
conductor is formed with an approximately rectangular flat shape,
and the split part is positioned at the approximate center of the
outer edge corresponding to a long side among the four outer edges
of the C-shaped conductor.
9. An antenna array comprising a plurality of antennas according to
claim 1.
10. A radio communication apparatus comprising the antenna
according to claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to an antenna, an antenna
array, and a radio communication apparatus.
BACKGROUND ART
[0002] In recent years, orthogonal dual-polarized antennas and
orthogonal dual-polarized antenna arrays in which
multi-input-multi-output (MIMO) communications can be achieved by
polarization diversity have been in practical use, for example, as
base stations for mobile communications or antenna apparatuses for
Wi-Fi communication devices to ensure communication capacity. Most
of the orthogonal dual-polarized antennas and the orthogonal
dual-polarized antenna arrays are composed of two antenna elements
that are arranged to be substantially vertical to each other and an
array of the antenna elements. In order to prevent a decrease in
the communication capacity, it is required to suppress the coupling
between the two antenna elements. While the coupling between the
two antenna elements can be suppressed by separating the two
antenna elements, it is also required to increase the integration
degree of the antenna elements and to reduce the size of the
antenna in order to reduce the size of the whole apparatus.
[0003] Antennas disclosed in Patent Literature 1, 2, and 3 are
examples of the above orthogonal dual-polarized antenna. These
antennas have a structure in which two antenna elements (in these
examples, dipole antennas) are arranged in a cross shape so that
the centers of the respective antenna elements overlap and become
orthogonal to each other, whereby it is possible to reduce the size
of the whole antenna while suppressing the coupling between the two
antenna elements.
CITATION LIST
Patent Literature
[Patent Literature 1] Japanese Patent No. 4073130
[Patent Literature 2] Japanese Unexamined Patent Application
Publication No. 2006-352293
[Patent Literature 3] Japanese Unexamined Patent Application
Publication No. 2009-124403
SUMMARY OF INVENTION
Technical Problem
[0004] When the two antenna elements are arranged in such a way
that the centers of the respective antenna elements overlap each
other as stated above, however, one antenna element needs to be
cut, whereby the structure of the antenna elements becomes
complicated and it becomes difficult to manufacture the antenna
elements. In addition, since feed lines to the respective antenna
elements come close to each other, the coupling between the two
antenna elements may be increased due to the electromagnetic
coupling via the feed lines.
[0005] The present invention aims to provide a dual-polarized
antenna in which the integration degree of the antenna elements is
increased and the size of the whole antenna is reduced while
suppressing the coupling between the two antenna elements without
overlapping the two antenna elements.
Solution to Problem
[0006] In one aspect of the present invention, an antenna includes:
a conductive reflector; and two antenna elements that are arranged
to be spaced apart from each other, in which, in a projected view
on the conductive reflector, longitudinal directions of the two
antenna elements are substantially orthogonal to each other and an
end part of one of the two antenna elements in the longitudinal
direction is positioned around the center of the other one of the
antenna elements in the longitudinal direction.
Advantageous Effects of Invention
[0007] According to the present invention, it is possible to
provide a dual-polarized antenna in which the integration degree of
the antenna elements is increased and the size of the whole antenna
is reduced while suppressing the coupling between the two antenna
elements without overlapping the two antenna elements.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a perspective view of an antenna;
[0009] FIG. 2 is a front view of the antenna;
[0010] FIG. 3 is a plan view of the antenna;
[0011] FIG. 4 is a front view of a radio communication
apparatus;
[0012] FIG. 5 is a plan view of an antenna array;
[0013] FIG. 6 is a front view of the radio communication
apparatus;
[0014] FIG. 7 is a perspective view of a modified example of the
antenna;
[0015] FIG. 8 is a front view of a modified example of an antenna
element;
[0016] FIG. 9 is a front view of a modified example of the antenna
element;
[0017] FIG. 10 is a perspective view of a modified example of the
antenna element;
[0018] FIG. 11 is a perspective view of a modified example of the
antenna element;
[0019] FIG. 12 is a perspective view of a modified example of the
antenna element;
[0020] FIG. 13 is a front view of a modified example of the antenna
element;
[0021] FIG. 14 is a front view of a modified example of the antenna
element;
[0022] FIG. 15 is a front view of a modified example of the antenna
element;
[0023] FIG. 16 is a front view of a modified example of the antenna
element;
[0024] FIG. 17 is a perspective view of a modified example of the
antenna element;
[0025] FIG. 18 is a perspective view of a modified example of the
antenna element;
[0026] FIG. 19 is a perspective view of a modified example of the
antenna element;
[0027] FIG. 20 is a perspective view of a modified example of the
antenna element;
[0028] FIG. 21 is a perspective view of a modified example of the
antenna element;
[0029] FIG. 22 is a perspective view of a modified example of the
antenna;
[0030] FIG. 23 is a perspective view of a modified example of the
antenna;
[0031] FIG. 24 is a front view of a modified example of the
antenna;
[0032] FIG. 25 is a front view of a modified example of the
antenna;
[0033] FIG. 26 is a front view of a modified example of the
antenna;
[0034] FIG. 27 is a perspective view of a modified example of the
antenna;
[0035] FIG. 28 is a perspective view of a modified example of the
antenna;
[0036] FIG. 29 is a perspective view of a modified example of the
antenna;
[0037] FIG. 30 is a front view of a modified example of the
antenna;
[0038] FIG. 31 is a perspective view of a modified example of the
antenna;
[0039] FIG. 32 is a front view of a modified example of the antenna
element;
[0040] FIG. 33 is a plan view of a modified example of the antenna
array; and
[0041] FIG. 34 is a plan view of a modified example of the antenna
array.
DESCRIPTION OF EMBODIMENTS
[0042] Hereinafter, with reference to the drawings, embodiments of
the present invention will be described in detail. Although
technically preferred limitation to carry out the present invention
is made to the embodiments described below, the scope of the
present invention is not limited to the following description.
First Embodiment
[0043] An antenna 10 according to a first embodiment of the present
invention will be described below.
[0044] FIG. 1 is a perspective view of the antenna 10, FIG. 2 is a
front view of the antenna 10, and FIG. 3 is a plan view of the
antenna 10. In FIGS. 1 and 2, the antenna 10 includes a conductive
reflector 101 and two antenna elements 102 and 103 above a surface
of the conductive reflector 101. As shown in FIG. 3, in a projected
view on the conductive reflector 101, longitudinal directions of
the two antenna elements 102 and 103 are substantially orthogonal
to each other and an end part 110 of the antenna element 103 in the
longitudinal direction (in FIG. 3, y-axis direction) is positioned
near an approximate center 109 (part around the center) of the
antenna element 102 in the longitudinal direction. The two antenna
elements 102 and 103 are arranged so as to be spaced apart from
each other.
[0045] As shown in FIGS. 1 and 2, the antenna elements 102 and 103
each include, for example, a dielectric layer 108, a C-shaped
conductor 104 that is formed on one side of the dielectric layer
108, has a substantially C shape, and serves as a split-ring
resonator, a conductor feed line 105 that is formed on the other
side of the dielectric layer 108 and is opposed to the C-shaped
conductor 104 with an interval therebetween, a conductive via 106
that electrically connects a part on the long side of the C-shaped
conductor 104 that is apart from the conductive reflector 101
(z-axis positive direction side) and one end of the conductor feed
line 105, and a feeding point 107 capable of electrically exciting
a part between the other end of the conductor feed line 105 and the
neighboring C-shaped conductor 104.
[0046] The dielectric layer 108 may not be shown in the drawings to
simplify the description. The dielectric layer 108 may not be shown
in the drawings in order to facilitate the understanding of the
technique of the present invention.
[0047] The conductive reflector 101, the C-shaped conductor 104,
the conductor feed line 105, the conductive via 106, and the other
conductors are made of metal such as copper, silver, aluminum, or
nickel, or other good conductor materials. Further, although the
C-shaped conductor 104, the conductor feed line 105, the conductive
via 106, and the dielectric layer 108 are typically manufactured in
a process for manufacturing a normal substrate such as a printed
board or a semiconductor substrate, they may be manufactured by
another method. Furthermore, although the conductive via 106 is
typically formed by plating a through-hole that is formed on the
dielectric layer 108 by a drill, any other method may be used as
long as the layers can be electrically connected. The conductive
via 106 may be formed by using, for example, a laser via formed by
a laser, a copper line or the like.
[0048] Further, the dielectric layer 108 may be omitted or the
parts of the dielectric layer 108 other than a partial dielectric
material support member may be hollow. The feeding point 107 is
connected, for example, to a radio communication circuit (not
shown) or a transmission line (not shown) that transmits radio
signals from the radio communication circuit so that radio
communication signals can be transmitted between the radio
communication circuit and the antenna 10. Further, while the
conductive reflector 101 is typically formed of copper foil bonded
to a sheet metal or a dielectric substrate, it may be formed of
another material as long as it is conductive.
[0049] The antenna 10 described above is appropriately embedded in,
for example, radio communication apparatuses such as Wi-Fi and
mobile communication base stations as an antenna part.
[0050] FIG. 4 shows a radio communication apparatus 11, which is
one example of the radio communication apparatus including the
antenna 10. The radio communication apparatus 11 includes the
antenna 10, a dielectric radome 115 that mechanically protects the
antenna 10, a radio communication circuit 113, and a transmission
line 112 that transmits radio signals between an antenna element in
the antenna 10 and the radio communication circuit 113.
[0051] Further, FIG. 5 shows an antenna array 12 in which a
plurality of antennas 10 are arranged in such a way that they are
spaced apart from one another by about 1/2 of the wavelength of
electromagnetic waves of the resonance frequency of the antenna
element and FIG. 6 shows a radio communication apparatus 13, which
is one example of the radio communication apparatus including the
antenna array 12. Instead of providing one conductive reflector 101
for each antenna 10, one conductive reflector 101 in which all the
conductive reflectors are connected in the form of a plate is used
in the antenna array 12. However, the configuration of the
conductive reflector 101 is not limited to this example. Further,
when a plurality of antennas 10 are arranged, they are not
necessarily arranged at regular intervals and translationally
symmetric and may be oriented in various directions and arranged at
irregular intervals. The radio communication apparatus 13 includes
the antenna array 12, the dielectric radome 115, the transmission
line 112, and a radio communication circuit unit 114.
[0052] The radio communication apparatus 11 and the radio
communication apparatus 13 are used, for example, as the radio
communication apparatus or the mobile communication base station,
and may further include, for example, a baseband processor that
performs baseband processing and the like. Further, beam forming
may be performed by controlling input signals to co-polarized
antenna elements in the antenna array 12 by the radio communication
circuit unit 114 or the like.
[0053] The functions and the effects of the embodiment of the
present invention will now be described.
[0054] The present inventors have conducted a detailed
investigation of an electromagnetic field that is generated around
the two antenna elements 102 and 103 when the two antenna elements
102 and 103 are electromagnetically resonated and have found that
parts around both of the end parts 110 of the two antenna elements
102 and 103 in the longitudinal direction (the longitudinal
direction of the antenna element 102 corresponds to the x-axis
direction in FIG. 3 and the longitudinal direction of the antenna
element 103 corresponds to the y-axis direction in FIG. 3) become
electrically open planes, in which the electric field strength is
high and the magnetic field strength is low and parts around the
approximate centers 109 become electrically short-circuited planes,
in which the magnetic field strength is high and the electric field
strength is low.
[0055] In the antenna 10 according to the present invention, the
two antenna elements 102 and 103 do not overlap each other in a
cross shape and are arranged to be substantially orthogonal to each
other with an interval therebetween so that the approximate center
109 of one antenna element and the end part 110 of the other
antenna element in the longitudinal direction become close to each
other.
[0056] According to the above arrangement, in each of the electric
field and the magnetic field, the two antenna elements are
orthogonally arranged in such a way that the components that have
the high strength do not come close to each other, whereby it is
possible to arrange the two antenna elements in such a way that
they come close to each other while suppressing the coupling
between them. Further, in this case, the distance between the
feeding points 107 of both elements increases and there is no
region where the elements physically overlap each other in view of
the structure of the elements, whereby it is possible to avoid the
manufacturing complexity while suppressing the coupling, which is
due to the feed parts coming close to each other. However, since
the conductors are close to each other in a split part 111 of the
C-shaped conductor 104 in FIG. 2, the electric field strength of
the split part 111 is high although the split part 111 is at the
center of each of the two antenna elements 102 and 103. However,
the electric field strength of only a small space between the
conductor parts that are opposed to each other becomes high and the
electric field strength is abruptly decreased in a part away from
the split part 111. Therefore, the fact that the split part 111 has
a high electric field strength does not affect the effects of the
present invention.
[0057] According to the above structure, it is possible to provide
a dual-polarized antenna in which antenna elements are highly
integrated and the size of the whole antenna is reduced while
suppressing coupling between the two antenna elements without
having two antenna elements overlap each other and a communication
apparatus and a communication system that use the dual-polarized
antenna.
[0058] More preferably, the aforementioned distance between the
approximate center 109 of one antenna element and the end part 110
of the other antenna element, which corresponds to a distance
between the antenna element 102 and the antenna element 103, is
made about one quarter of the wavelength or smaller when the array
antenna is formed for the purpose of suppressing the distance
between the plurality of dual-polarized antennas 10 to about the
half wavelength of the electromagnetic waves of the frequency to be
used.
[0059] Further, the two antenna elements 102 and 103 are not
necessarily inverted with respect to the conductive reflector 101
as shown in FIGS. 1 and 2 and may be, for example, parallel to the
conductive reflector 101 as shown in FIG. 7. When the structure in
which the two antenna elements 102 and 103 are made parallel to the
conductive reflector 101 is employed, the antenna elements 102 and
103 may be formed in one substrate having a common dielectric layer
108. In addition, when the array antenna in which a plurality of
antennas 10 are arranged is formed, the plurality of antennas 10
may be formed in one substrate as shown in FIG. 33. According to
the above structure, the number of processes for aligning the
plurality of antenna elements can be reduced, which makes the
assembling process easier. Further, when the structure in which the
two antenna elements 102 and 103 are made parallel to the
conductive reflector 101 is employed, in the antenna element that
is close to the other antenna element in the approximate center 109
(in FIG. 7, the antenna element 102), the end part of the antenna
element 102 in the approximate center 109 which does not include
the split part 111 preferably faces toward the antenna element 103
so that the coupling between the antenna elements is reduced. In
other words, when the structure in which the two antenna elements
102 and 103 are made parallel to the conductive reflector 101 is
employed, the split part 111 of the antenna element 102 opens in a
direction away from the antenna element 103 so that the coupling
between the antenna elements is reduced.
[0060] In addition, the two antenna elements 102 and 103 may not
necessarily have the structures shown in FIGS. 1 and 2 and further
modifications may be made on the structures thereof.
[0061] As shown in FIG. 8, for example, in order to improve the
dimensional accuracy of the end parts of the conductor pattern when
each of the two antenna elements 102 and 103 is formed, the
dielectric layer 108 may have a size larger than that of the
C-shaped conductor 104. Further, one end of the conductor feed line
105 may be directly connected in an electrically conductive manner
to the part on a long side of the C-shaped conductor 104 that is
away from the conductive reflector 101 and the conductive via 106
may not be provided. As shown in FIG. 9, for example, the conductor
feed line 105 may be a linear conductor such as a copper line.
Further, as shown in FIG. 10, when the feeding point 107 is
provided in the end part of each of the two antenna elements 102
and 103, the conductor feed line 105 may be formed of a plurality
of conductors and conductive vias for the purpose of preventing a
contact between the other end of the conductor feed line 105 and
the C-shaped conductor 104. Alternatively, as shown in FIG. 11, a
part of the long side of the C-shaped conductor 104 that is close
to the conductive reflector 101 may be cut out, the conductor feed
line 105 may be provided in the cut out part, and the feeding point
107 may be provided to electrically excite a part between the
conductor feed line 105 and the end parts of the C-shaped conductor
104 that form the cut out part. In this case, the C-shaped
conductor 104 and the conductor feed line 105 may be formed on one
layer so that the manufacturing process can be made simpler.
Optionally, in order to compensate for the degradation of resonance
characteristics of the split-ring resonator, which is due to the
part of the C-shaped conductor 104 being cut out, as shown in FIG.
12, the C-shaped conductor 104 may include a bridging conductor 116
that makes the cut out part of the split-ring resonator conductive
without allowing the cut out part to come in contact with the
conductor feed line 105.
[0062] In addition, modifications may be made on the two antenna
elements 102 and 103 to improve the electrical characteristics.
[0063] The split-ring resonator formed of the C-shaped conductor
104 serves as an LC series resonator in which the inductance by the
current flowing along the ring and the capacitance generated
between the conductors opposed to each other in the split part 111
are connected in series. In the vicinity of the resonance frequency
of the split-ring resonator, a large current flows through the
C-shaped conductor 104 and some of the current components
contribute to the radiation, whereby the split-ring resonator
formed of the C-shaped conductor 104 serves as an antenna. In this
case, current components of the two antenna elements 102 and 103 in
the longitudinal direction mainly contribute to the radiation in a
current that flows through the C-shaped conductor 104. It is
therefore possible to achieve excellent radiation efficiency by
increasing the length of the C-shaped conductor 104 in the
longitudinal direction. Although each of the antenna elements 102
and 103 has a substantially rectangular shape in FIGS. 1 and 2, the
two antenna elements 102 and 103 may each have another shape as
long as the two antenna elements 102 and 103 are arranged as shown
in FIGS. 1, 2, and 3. The shape of the two antenna elements 102 and
103 does not affect the essential effects of the present invention.
The two antenna elements 102 and 103 may be, for example, a square,
a circle, or a triangle, or have a bow tie shape.
[0064] Further, as shown in FIG. 13, the two antenna elements 102
and 103 may each include conductive radiation parts 117 on the
respective end parts of the C-shaped conductor 104 in the
longitudinal direction. According to such a structure, the current
components of the C-shaped conductor 104 in the longitudinal
direction which contributes to the radiation can be induced to the
radiation parts 117, whereby it is possible to improve the
radiation efficiency. While the case in which the side of the
radiation part 117 that is connected to the C-shaped conductor 104
has the length the same as that of the side of the C-shaped
conductor 104 that is connected to the radiation part 117 is shown
in FIG. 13, the shape of the radiation part 117 is not limited
thereto. As shown in FIGS. 14 and 15, for example, the side of the
radiation part 117 that is connected to the C-shaped conductor 104
may be longer than the side of the C-shaped conductor 104 that is
connected to the radiation part 117. When the antenna elements 102
and 103 include the radiation parts 117, the antenna elements 102
and 103, together with the C-shaped conductor 104 and the radiation
parts 117, may have a long side, whereby it is possible to achieve
excellent radiation efficiency. In this case, the C-shaped
conductor 104 does not necessarily have a long side in the
longitudinal directions of the antenna elements 102 and 103. The
shape of the C-shaped conductor 104 may be, for example, a
rectangular shape having a long side in the z axis direction as
shown in FIG. 32 (see FIG. 1 as well), or may be a square, a
circle, or a triangle.
[0065] Further, the resonance frequency of the split-ring resonator
formed by the C-shaped conductor 104 can be reduced by increasing
the inductance by making the size of the ring of the split ring
larger and making the current path longer, or by increasing the
capacitance by narrowing the gap between the conductors opposed to
each other in the split part 111. The above capacitance may be
increased by increasing, for example, the area of the C-shaped
conductors 104 that are opposed to each other and form the split
part 111 as shown in FIG. 16. Alternatively, as shown in FIGS. 17
and 18, auxiliary conductor patterns 118 may be provided in a layer
that is different from the layer where the C-shaped conductor 104
is formed and the auxiliary conductor patterns 118 may be connected
to the split part 111 by conductive vias 119, to thereby increase
the area of the conductors opposed to each other in the split part
111 in the split-ring resonator. FIG. 17 shows a case in which the
auxiliary conductor patterns 118 are arranged in a layer the same
as the layer where the conductor feed line 105 is formed. FIG. 18
shows a case in which the auxiliary conductor patterns 118 are
arranged in a layer that is different from the layer where the
C-shaped conductor 104 is formed and the layer where the conductor
feed line 105 is formed. Further, as shown in FIG. 19, by providing
the auxiliary conductor pattern 118 only in one conductor of the
split part 111 and causing the auxiliary conductor pattern 118 and
at least a part of the other conductor of the split part 111 to be
opposed to each other between the layer of the C-shaped conductor
104 and the layer of the auxiliary conductor pattern 118, the area
of the conductors opposed to each other in the split part 111 may
be increased.
[0066] Further, by changing the connection position between the
conductor via 106 or one end of the conductor feed line 105 when
the conductive via 106 is not provided and the C-shaped conductor
104, the input impedance of the split-ring resonator seen from the
feeding point 107 can be changed. By matching the impedance of a
radio communication circuit (not shown) or a transmission line (not
shown) connected to the feeding point 107 with the input impedance
of the split-ring resonator, the radio communication signals can be
supplied to the antenna without reflections. However, even when the
impedances do not match each other, this does not affect the
fundamental effects of the present invention. In addition, as shown
in FIG. 20, a second C-shaped conductor 120 may be provided in a
layer different from the layers where the C-shaped conductor 104
and the conductor feed line 105 are formed and the C-shaped
conductor 104 and the second C-shaped conductor 120 may be
electrically connected to each other via a plurality of conductive
vias 121. In this case, the C-shaped conductor 104 and the second
C-shaped conductor 120 serve as one split-ring resonator. In this
case, the conductor feed line 105 is almost surrounded by the
C-shaped conductor 104 and the second C-shaped conductor 120 that
are electrically connected to each other and the plurality of
conductive vias 121. It is therefore possible to reduce radiation
of unwanted signal electromagnetic waves from the conductor feed
line 105. Further, as shown in FIG. 21, similar to FIG. 17, the
auxiliary conductor patterns 118 may be provided in a layer
different from the layers in which the C-shaped conductor 104 and
the second C-shaped conductor 120 are provided and connected to the
split part 111 and the second split part 122 via the conductive
vias 119. Since the area of the conductors opposed to each other in
the split part 111 and the second split part 122 increases due to
the presence of the auxiliary conductor patterns 118, it is
possible to increase the capacitance without increasing the size of
the whole resonator.
[0067] Further, since the conductive reflector 101 serves as a
short-circuited plane, it is more preferable that a distance Z
between the two antenna elements 102 and 103 and the conductive
reflector 101 shown in FIG. 2 be substantially one quarter of the
wavelength when the electromagnetic waves whose frequency is a
resonance frequency of the antenna elements travel through a
substance that fills the region in order to suppress the influence
of the antenna elements on the resonance characteristics. Even when
the distance Z is not substantially one quarter of the wavelength,
this does not affect the fundamental effects of the present
invention. Further, the distance Z in the antenna element 102 and
the distance Z in the antenna element 103 may be different from
each other.
[0068] In addition, in dipole antenna elements in which parts near
both of the end parts can be regarded as electrically open planes
and parts near the approximate centers can be regarded as
electrically short-circuited planes at resonance as well, by
employing the arrangement as shown in FIGS. 1, 2, and 3 in this
embodiment, as shown in FIG. 22, the dual-polarized antenna in
which the antenna elements are highly integrated and the size of
the whole antenna is reduced can be formed while suppressing the
coupling between the two antenna elements without having the two
antenna elements overlap each other. In FIG. 22, two dipole antenna
elements 201 and 202 each include a radiation part 203 formed of
two conductors that have a length of about the substantially half
wavelength and are arranged with an interval therebetween and the
feeding point 107 that excites the part between the two conductors
of the radiation part 203.
Second Embodiment
[0069] An antenna 20 according to a second embodiment of the
present invention will now be described.
[0070] FIG. 23 is a perspective view of the antenna 20 and FIG. 24
is a front view of the antenna 20. As shown in FIGS. 23 and 24, the
antenna 20 includes, in at least one or both of the two antenna
elements 102 and 103, a conductor feed GND part 123 having one end
connected to a part near the end part of the C-shaped conductor 104
opposed to the split part 111 and the other end connected to the
conductive reflector 101, the conductor feed GND part 123 being
opposed to the conductor feed line 105. In this embodiment, the
antenna 20 includes two conductor feed GND parts 123. One conductor
feed GND part 123 electrically connects the approximate center of
an outer edge of the antenna element 102 that extends in a C shape
and the conductive reflector 101. More specifically, one conductor
feed GND part 123 electrically connects the approximate center of
the outer edge that is opposed to the outer edge where the split
part 111 is formed among four outer edges of the antenna element
102 and the conductive reflector 101. The other conductor feed GND
part 123 electrically connects the approximate center of the outer
edge of the antenna element 103 that extends in a C shape and the
conductive reflector 101. More specifically, the other conductor
feed GND part 123 electrically connects the approximate center of
the outer edge that is opposed to the outer edge where the split
part 111 is formed among four outer edges of the antenna element
103 and the conductive reflector 101. Further, the conductor feed
line 105 and the dielectric layer 108 are extended on the side of
the conductive reflector 101. Then the feeding point 107 is
arranged near one of the end parts of the conductor feed line 105
that has been extended and is able to electrically excite a part
between the one of the end parts of the conductor feed line 105
that has been extended and the neighboring conductor feed GND part
123. While the conductor feed GND part 123 is connected to the
conductive reflector 101 in this example, it may not be connected
to the conductive reflector 101.
[0071] The antenna element 102 includes the C-shaped conductor 104
having a substantially C shape and the conductor feed line 105
having one end connected to the C-shaped conductor 104. The
C-shaped conductor 104 is formed by cutting out a part of a
substantially ring-shaped conductor. The C-shaped conductor 104
includes the split part 111, which corresponds to the cut out part
of the C-shaped conductor 104. The same is also applicable to the
antenna element 103.
[0072] The antenna element 102 includes the conductor feed GND part
123 arranged to be opposed to the conductor feed line 105. The
conductor feed GND part 123 has one end that is connected to the
outer edge of the C-shaped conductor 104. The conductor feed GND
part 123 has the other end that is connected to the conductive
reflector 101. That is, the conductor feed GND part 123
electrically connects the outer edge of the C-shaped conductor 104
and the conductive reflector 101. The same is also applicable to
the antenna element 103.
[0073] The outer edge of the C-shaped conductor 104 extends in a C
shape. One end of the conductor feed GND part 123 is connected to
the approximate center of the outer edge that extends in the C
shape. In other words, one end of the conductor feed GND part 123
is connected to the approximate center of the outer edge that is
opposed to the outer edge where the split part 111 is formed among
four outer edges included in the C-shaped conductor 104.
[0074] The antenna 20 and the antenna 10 according to the first
embodiment are the same except for the point stated above.
[0075] The effects of the second embodiment will now be
described.
[0076] When the transmission line that transmits radio signals is
connected to each of the two antenna elements 102 and 103 via the
feeding point 107, the conductor is connected to the resonator.
[0077] Therefore, the resonance characteristics of the two antenna
elements 102 and 103 may be changed depending on the arrangement
and the shape of the transmission lines near the two antenna
elements 102 and 103.
[0078] However, the parts in the antenna 20 in which the conductor
feed GND parts 123 are connected to the two respective antenna
elements 102 and 103 are positioned at the approximate centers of
the antenna elements. As described in the first embodiment, these
parts of the C-shaped conductors, which are resonators, are
electrically short-circuited planes at resonance. In this case, the
present inventors have found that the conductor feed GND parts 123
do not increase extra capacitance or inductance that may affect the
resonance characteristics, and therefore the resonance
characteristics of the two antenna elements 102 and 103 are not
substantially changed.
[0079] Accordingly, by extending the conductor feed line 105 so
that it becomes opposed to the conductor feed GND part 123, it is
possible to form a transmission line that is composed of the
conductor feed line 105 that has been extended and the conductor
feed GND part 123, which are two conductors that are opposed to
each other, and is connected to the antenna elements without
affecting the resonance characteristics. By providing the feeding
point 107 at the tip of the transmission line, the distance between
another transmission line connected to the feeding point 107 and
the two antenna elements 102 and 103 can be increased, whereby it
is possible to reduce the influence of the transmission line on the
two antenna elements 102 and 103.
[0080] As described above, it is possible to provide a
dual-polarized antenna in which the influence of the transmission
line on the resonance characteristics of the antenna elements is
suppressed and a communication apparatus and a communication system
that use the dual-polarized antenna.
[0081] Note that all the modified examples of the two antenna
elements 102 and 103 described in the first embodiment may be
applied also to the two antenna elements 102 and 103 according to
this embodiment. The antenna elements 102 and 103 may be, for
example, parallel to the conductive reflector 101, as shown in FIG.
7. In this case, the conductor feed GND part 123 may be formed of a
plurality of conductive vias in the substrate, the conductor feed
line 105 opposed to the conductor feed GND part 123 may be formed
of a conductive via in the same substrate, and all the components
including the antenna elements 102 and 103 that have the common
conductive reflector 101 and the common dielectric layer 108 may be
formed in an integrated substrate.
[0082] Further, in an array antenna in which a plurality of
antennas 20 according to this embodiment are arranged, as shown in
FIG. 34, among the antenna elements 102 and the conductor feed GND
parts 123 coupled to the antenna elements 102 of the plurality of
antennas 20, the antenna elements 102 and the conductor feed GND
parts 123 that are arranged on one plane may be formed on the
dielectric layer 108 while integrating the dielectric layer 108.
The same is also applicable to the antenna elements 103 and the
conductor feed GND parts 123 coupled to the antenna elements 103 of
the plurality of antennas 20. By forming the array antenna as
stated above, the steps required to align the plurality of antenna
elements and the plurality of conductor feed GND parts 123 can be
reduced. In this case, however, one of the dielectric layers 108
that are orthogonal to each other needs to be partially cut.
[0083] Further, as described above, the conductor feed GND part 123
is preferably connected to the outer edge of each of the antenna
elements 102 and 103 corresponding to the approximate center of the
antenna elements 102 and 103, which are electrically
short-circuited planes at resonance. More specifically, the planes
that include the center of the antenna elements 102 and 103 and are
orthogonal to the longitudinal directions of the antenna elements
102 and 103 (102 is arranged along the x-axis direction and 103 is
arranged along the y-axis direction) serve as electrically
short-circuited planes at resonance. Since the planes which are in
the range of 1/4 of the size of the antenna elements 102 and 103 in
the longitudinal directions (when the antenna elements 102 and 103
include the radiation parts 117, the size of the antenna elements
102 and 103 plus the radiation parts 117) in the antenna element
longitudinal direction from the electrically short-circuited plane
can be regarded as short-circuited planes, the conductor feed GND
parts 123 are preferably positioned within this range. Therefore,
the size of the conductor feed GND parts 123 in the antenna element
longitudinal direction is preferably equal to or smaller than 1/2
of the size of the antenna element in the longitudinal direction.
Even when the conductor feed GND parts 123 are positioned outside
the above range, this does not affect the fundamental effects of
the present invention. Further, even when the size of the conductor
feed GND parts 123 in the antenna element longitudinal direction is
outside the above range, this does not affect the fundamental
effects of the present invention.
[0084] While each of the conductor feed GND parts 123 has one end
that is connected to the approximate center of the end part of each
of the antenna elements 102 and 103 corresponding to a part of the
C-shaped conductor 104 that is opposed to the split part 111 in
FIGS. 23 and 24, the conductor feed GND part 123 may be connected
to another part of the C-shaped conductor 104 as shown in FIG. 25
as long as the connection of the conductor feed GND part 123 has no
great influence on the resonance characteristics of the two antenna
elements 102 and 103.
[0085] Further, the input impedance to the antenna seen from the
feeding point 107 depends on the connection position between the
conductive via 106 or one end of the conductor feed line 105 when
the conductive via 106 is not provided and the C-shaped conductor
104, as described in the first embodiment. In the antenna 20
according to this embodiment, however, the input impedance to the
antenna also depends on the characteristic impedance of the
transmission line formed of the conductor feed line 105 that has
been extended and the conductor feed GND part 123. By matching the
characteristic impedance of the aforementioned transmission line
with the input impedance of the split-ring resonator, the radio
communication signals may be supplied to the antenna without
reflections between the aforementioned transmission line and the
split-ring resonator. Even when the impedances do not match, this
does not affect the essential effects of the present invention.
[0086] Further, as shown in FIG. 26, the transmission line formed
of the above extended conductor feed line 105 and the conductor
feed GND part 123 may be a coplanar line and the C-shaped conductor
104, the conductor feed line 105, and the conductor feed GND part
123 may be formed on one layer. In this case, in each of the two
antenna elements 102 and 103, as shown in FIGS. 11 and 12 in the
first embodiment, a part of the long side of the C-shaped conductor
104 which is close to the conductive reflector 101 is cut out and
the conductor feed line 105 is provided in the cut out part. Then,
the aforementioned cut out part is directly connected to the slit
of the conductor feed GND part 123 and the conductor feed line 105
is further extended in the direction of the conductive reflector
101 and passes through the slit, whereby the transmission line
formed of the aforementioned conductor feed line 105 and the
conductor feed GND part 123 can serve as the coplanar line.
[0087] Further, as shown in FIG. 27, in the antenna 20, the two
antenna elements 102 and 103 may each include the second C-shaped
conductor 120 and the plurality of conductive vias 121, as shown in
FIGS. 20 and 21 in the first embodiment and further include a
second conductor feed GND part 124 and a plurality of conductive
vias 125. The second conductor feed GND part 124 is connected to
the second C-shaped conductor 120 in a way similar to the way that
the conductor feed GND part 123 is connected to the C-shaped
conductor 104 and is opposed to the conductor feed line 105. The
plurality of conductive vias 125 then electrically connect the
conductor feed GND part 123 and the second conductor feed GND part
124. In this case, a large part of the conductor feed line 105 is
surrounded by, besides the C-shaped conductor 104 and the second
C-shaped conductor 120 that are electrically connected to each
other and the plurality of conductive vias 121, by the second
conductor feed GND part 124 and the plurality of conductive vias
125. It is therefore possible to reduce radiation of unwanted
signal electromagnetic waves from the conductor feed line 105.
[0088] Further, as shown in FIG. 28, the transmission line formed
of the aforementioned extended conductor feed line 105 and the
conductor feed GND part 123 may be a coaxial line.
[0089] Further, as shown in FIGS. 29 and 30, a clearance 126 may be
provided in the conductive reflector 101 and a connector 127 may be
provided on a rear side (z-axis negative direction side) of the
conductive reflector 101. In this case, an external conductor 129
of the connector 127 is electrically connected to the conductive
reflector 101. Then a core wire 128 of the connector 127 passes
inside the clearance 126, penetrates through the front side (z-axis
positive direction side) of the conductive reflector 101, and is
electrically connected to the conductor feed line 105 of the
antenna elements 102 and 103. Further, the feeding point 107 is
capable of electrically exciting a part between the core wire 128
of the connector 127 and the external conductor 129. According to
the structure stated above, power can be supplied to the two
antenna elements 102 and 103 on the front side of the conductive
reflector 101 from the radio communication circuit, a digital
circuit or the like arranged on the rear side of the conductive
reflector 101, whereby the radio communication apparatus can be
formed without greatly affecting the radiation pattern and the
radiation efficiency.
[0090] Furthermore, in the two antenna elements 102 and 103,
similar to the first embodiment, the conductive reflector 101
serves as the short-circuited plane. Therefore, in order to
suppress the influence of the antenna elements on the resonance
characteristics, as shown in FIG. 24, it is more preferable that
the distance Z between the two antenna elements 102 and 103 and the
conductive reflector 101 be substantially one quarter of the
wavelength when the electromagnetic waves whose frequency is a
resonance frequency of the antenna elements travel through a
substance that fills the region. Even when the distance Z is not
substantially one quarter of the wavelength, this does not affect
the fundamental effects of the present invention. Further, the
distance Z in the antenna element 102 and the distance Z in the
antenna element 103 may be different from each other.
[0091] Further, as described in the first embodiment, it can be
regarded that the part about the approximate center of each of the
dipole antenna elements is the electrically short-circuited plane
at resonance. Therefore, as shown in FIG. 31, even when the dipole
antenna elements 201 and 202 are used, by connecting the conductor
feed GND part 123 to the approximate center of each of the dipole
antenna elements 201 and 202, it is possible to form the
transmission line connected to the antenna element without
affecting the resonance characteristics. In this case, as shown in
FIG. 31, the antenna 20 includes the conductor feed GND part 123
having one end connected to one of two conductor parts of the
radiation part 203 and the other end connected to the conductive
reflector 101, the conductor feed line 105 that is opposed to the
conductor feed GND part 123 and has one end connected to the other
one of the two conductor parts of the radiation part 203 and the
other end extended toward the conductive reflector 101, and the
feeding point 107 that excites the part between one end of the
conductor feed line 105 that is extended and the neighboring
conductor feed GND part 123, the other structures of the antenna 20
being the same as the structures in the first embodiment as shown
in FIG. 22.
[0092] As a matter of course, the aforementioned embodiments and
the plurality of modified examples described above may be combined
within a range in which the contents thereof do not conflict with
each other. Moreover, though the functions and the like of each
component have been described in detail in the embodiments and the
modified examples described above, they may be changed in various
ways within a range that satisfies the invention of the present
application.
[0093] The first and second embodiments have been described above.
The embodiments described above have the following
characteristics.
(1) As shown in FIG. 1, the antenna 10 includes the conductive
reflector 101 and the two antenna elements 102 and 103 (antenna
elements) that are arranged to be spaced apart from each other. As
shown in FIG. 3, in a projected view on the conductive reflector
101, the longitudinal directions of the two antenna elements 102
and 103 are substantially orthogonal to each other. The end part
110 of the antenna element 103 in the longitudinal direction is
positioned at the approximate center 109 (part around the center)
of the antenna element 102 in the longitudinal direction. (2) As
shown in FIG. 22, the antenna elements 102 and 103 may be the
dipole antenna elements 201 and 202, respectively. (3) As shown in
FIG. 2, each of the antenna elements 102 and 103 includes the
C-shaped conductor 104 having the substantially C shape that is
formed by cutting out a part of the substantially ring-shaped
conductor and the conductor feed line 105 having one end connected
to the C-shaped conductor 104. The C-shaped conductor 104 includes
the split part 111, which corresponds to the notch formed in the
C-shaped conductor 104. (4) As shown in FIGS. 23 and 24, each of
the antenna elements 102 and 103 includes the conductor feed GND
part 123 that is arranged so that it is opposed to the conductor
feed line 105. The conductor feed GND part 123 has one end
connected to the outer edge of the C-shaped conductor 104. The
conductor feed GND part 123 has the other end connected to the
conductive reflector 101. (5) As shown in FIG. 24, one end of the
conductor feed GND part 123 is connected to the approximate center
of the outer edge of the C-shaped conductor 104. In the example
shown in FIG. 24, one end of the conductor feed GND part 123 is
connected to the approximate center of the outer edge of the
C-shaped conductor 104 on the side of the conductive reflector 101.
(6) As shown in FIG. 19, each of the antenna elements 102 and 103
includes at least one auxiliary conductor pattern 118 that is
electrically connected to one of the two conductors of the C-shaped
conductor 104 opposed to each other in the split part 111 and is
opposed to the other one of the two conductors thereof. The
auxiliary conductor pattern 118 is opposed to the other conductor
in, for example, the thickness direction of the C-shaped conductor
104. (7) As shown in FIGS. 13 to 15 and 32, the C-shaped conductor
104 is formed with an approximately rectangular flat shape. Each of
the antenna elements 102 and 103 includes the conductor radiation
part 117 connected to at least one of two outer edges adjacent to
the outer edge where the split part 111 is formed among four outer
edges of the C-shaped conductor 104. In this embodiment, each of
the antenna elements 102 and 103 includes a pair of conductor
radiation parts 117 connected to the two respective outer edges
adjacent to the outer edge where the split part 111 is formed among
the four outer edges of the C-shaped conductor 104. (8) As shown in
FIG. 2, the C-shaped conductor 104 is formed with an approximately
rectangular flat shape. The split part 111 is positioned at the
approximate center of the outer edge corresponding to a long side
among the four outer edges of the C-shaped conductor 104. (9) As
shown in FIG. 5, the antenna array 12 includes the plurality of
antennas 10. (10) As shown in FIG. 4, the radio communication
apparatus 11 includes the antenna 10. As shown in FIG. 6, the radio
communication apparatus 13 includes the antenna array 12.
(Supplementary Note 1)
[0094] An antenna comprising:
[0095] a conductive reflector; and
[0096] two antenna elements that are arranged to be spaced apart
from each other,
[0097] wherein the two antenna elements are arranged so that, in a
projected view on the conductive reflector, longitudinal directions
of the antenna elements are substantially orthogonal to each other
and an approximate center of one of the antenna elements is
arranged on a line obtained by extending the other one of the
antenna elements in the longitudinal direction.
(Supplementary Note 2)
[0098] The antenna according to Supplementary Note 1, wherein the
antenna element comprises:
[0099] a C-shaped conductor that is continuously formed in a
substantially C shape; and
[0100] a conductor feed line having one end that is electrically
connected to a part of the C-shaped conductor,
[0101] wherein a projection of the conductor feed line on a plane
of the C-shaped conductor that forms the substantially C shape
partially overlaps an opening formed in the C-shaped conductor.
[0102] While the present invention has been described above with
reference to the embodiments, the present invention is not limited
to the above embodiments. Various changes that may be understood by
those skilled in the art may be made on the configurations and the
details of the present invention within the scope of the present
invention.
[0103] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2014-73195, filed on
Mar. 31, 2014, the disclosure of which is incorporated herein in
its entirety by reference.
REFERENCE SIGNS LIST
[0104] 10, 20 ANTENNA [0105] 11, 13 RADIO COMMUNICATION APPARATUS
[0106] 12 ANTENNA ARRAY [0107] 101 CONDUCTIVE REFLECTOR [0108] 102,
103 ANTENNA ELEMENT [0109] 104, 120 C-SHAPED CONDUCTOR [0110] 105
CONDUCTOR FEED LINE [0111] 106, 119, 121, 125 CONDUCTIVE VIA [0112]
107 FEEDING POINT [0113] 108 DIELECTRIC LAYER [0114] 109
APPROXIMATE CENTER OF ANTENNA ELEMENT [0115] 110 END PART OF
ANTENNA ELEMENT IN LONGITUDINAL DIRECTION [0116] 111, 122 SPLIT
PART [0117] 112 TRANSMISSION LINE [0118] 113 RADIO COMMUNICATION
CIRCUIT [0119] 114 RADIO COMMUNICATION CIRCUIT UNIT [0120] 115
RADOME [0121] 116 BRIDGING CONDUCTOR [0122] 117 RADIATION PART
[0123] 118 AUXILIARY CONDUCTOR PATTERN [0124] 123, 124 CONDUCTOR
FEED GND PART [0125] 126 CLEARANCE [0126] 127 CONNECTOR [0127] 128
CORE WIRE [0128] 129 EXTERNAL CONDUCTOR [0129] 201, 202 DIPOLE
ANTENNA ELEMENT [0130] 203 RADIATION PART [0131] Z DISTANCE BETWEEN
ANTENNA ELEMENTS 102 AND 103 AND CONDUCTIVE REFLECTOR 101
* * * * *